If A and B are coefficients of xn in the expansions of (1 + x)2n and (1 + x)2n–1 respectively, then A/B equals to
(a) 1
(b) 2
(c)
(d)
The answer is the option (b) 2
2nCn is the coefficient of xn in the expansion of (1+x)2n
Thus, A = 2nCn
&2n-1Cn is the coefficient of xn in the expansion of (1+x)2n-1
Thus, B = 2n-1Cn
Thus, A/B = 2nCn/2n-1Cn
= 2/1
=2:1